The present invention relates to a braking device and a hoisting machine having the braking device, which are suitable for use, particularly, in elevator systems.
An elevator system provided with a hoisting machine is disclosed in P2000-16727A. This elevator system comprises a support arranged at an upper part of a hoistway and a hoisting machine supported thereon. The hoisting machine comprises a sheave on which a rope is wound to support a car.
With the above elevator system, however, there arises a problem that a braking device is increased in size in the radial direction, which causes upsizing of the hoisting machine provided with the braking device. On the other hand, along a recent tendency of elimination of a machine room in the field of elevators, the hoisting machine is often disposed in the hoistway of the elevator system, requiring downsizing of the hoisting machine.
It is, therefore, an object of the present invention to provide a braking device and a hoisting machine having the braking device, which are reduced in size.
The present invention provides generally an arrangement which comprises: a rotatable brake wheel; a pair of rotation shafts; a pair of brake arms, the brake arms being rotatably supported through the rotation shafts; a pair of brake pads each arranged at one end of the corresponding brake arm, the brake pads contacting and separating from the brake wheel; and a brake part connected to another end of the brake arms, the brake part providing and releasing a braking force of the brake pads, wherein when centers of the rotation shafts are fulcrums, centers of contact of the brake pads with the brake wheel are points of action, and connections between the brake arms and the brake part are power points, the fulcrums, the points of action, and the power points are located in a semicircular area of the brake wheel.